顾及植被形态结构异质性的极化干涉SAR林下地形反演研究

The high-accuracy digital terrain model (DTM) acquisition in forest cover areas is affected strongly by forest height, and Polarimetric SAR interferometry (PolInSAR) provides an opportunity to solve this problem. However, the current scattering model in PolInSAR forest parameter inversion does not fully consider the heterogeneity of vegetation morphology and structure, i.e., the heterogeneity of vegetation particle morphology and vegetation vertical structure. Moreover, complex coherence-based parameters solving only use partial polarimetric interferometric information, and cannot fully take into account vegetation morphology feature parameters. To address these issues, this project intends to carry out the research on PolInSAR underlying topography inversion taking into account heterogeneity of vegetation morphology and structure. In detail, this project plans to study PolSAR volume scattering model considering the heterogeneity of particle morphology and its applicability. On this basis, the PolInSAR scattering model taking into account the heterogeneity of vegetation particle morphology and vegetation vertical structure is constructed. Finally, coherence matrix T6-based multi-baseline PolInSAR method is developed and used for estimating parameters of forest height and underlying topography. For validation, experiments over different types of forest areas with multi-frequency multiple-baseline PolInSAR data are carried out. This project is of great significance in solving the technical problem of removing forest height effects in the topography mapping over forest area and promoting the development of PolInSAR technology.

森林覆盖区的高精度数字地形模型(DTM)获取会受到森林高度的严重影响，而极化干涉SAR技术(PolInSAR)为解决这一难题提供了契机。然而，当前的PolInSAR森林参数反演模型没有充分考虑植被形态结构异质性，即植被粒子形态异质性和植被垂直结构异质性，且基于复相干性的参数解算只利用了部分极化干涉信息，无法全面考虑植被形态特征参数。鉴于此，本项目拟开展顾及植被形态结构异质性的极化干涉SAR林下地形反演研究。具体地，本项目拟研究顾及植被粒子形态异质性的极化SAR体散射模型及其适用性；在此基础上，建立顾及植被粒子形态和垂直结构异质性的极化干涉SAR散射模型；最后发展基于相干矩阵T6的多基线极化干涉方法，协同反演森林高度和林下地形，并基于覆盖不同类型森林区的多波段多基线PolInSAR数据开展实验验证。本项目对解决森林区地形测绘中去除森林高度的技术难题及推动极化干涉SAR技术发展具有重要意义。

针对现有极化干涉SAR森林参数反演未充分考虑植被形态结构异质性的问题，本项目主要开展了极化SAR体散射模型、极化干涉SAR散射模型以及多基线森林高度和林下地形反演应用等三方面内容。项目揭示了不同植被粒子形态特征条件下的植被对极化散射机理的影响规律；建立了多种顾及植被粒子形态异质性的极化SAR体散射模型及模型评价方法；在此基础上建立了顾及植被粒子形态异质性、地形坡度、垂直结构异质性的极化干涉SAR散射模型；基于极化干涉T6矩阵建立了植被粒子形态特征与极化干涉SAR观测量之间的关联；在不同森林和低矮植被区域开展了一系列植被高度和林下地形反演应用，可以为植被区极化(干涉)SAR散射机理解译与建模、植被分类、植被高度和林下地形反演提供技术参考。项目已发表了SCI期刊论文11篇，EI期刊论文1篇，EI会议论文1篇，申请国家发明专利2项。